Tangential flow pumping stages have previously been incorporated in turbomolecular pumps, an example of which is disclosed in European Patent Application Publication No. EP 0,445,855 assigned to the assignee of the present application.
The cited '855 publication pertains to a turbomolecular pump which, in addition to conventional axial flow pumping stages, utilizes one or more tangential flow pumping stages, wherein the stator ring surrounding the rotor disk and the rotor disk surfaces are substantially parallel, thereby defining a pumping channel therebetween of substantially rectangular cross-section and uniform width.
Research carried out testing the operational characteristics of the tangential channels of the aforementioned pumps has shown that the enlarged modifications of the rectangular cross-section of the pumping channel lead to the impressive restricts in terms of pumping speed compression ratio.
Accordingly, one of the advantages of the present invention is a tangential flow pumping channel of improved design, as part of one or more tangential flow pumping stages in an axial flow turbomolecular pump, which is designed to substantially improve the above-identified operational characteristics of said turbomolecular pump.
A further advantage of the present invention is a pumping channel of improved design as an element of a turbomolecular pump which can be easily manufactured at a low cost.